Your dmesg does not contain anything at all about amdgpu. It seems it was cut off at the beginning. You can temporarily make the AMD-Vi error go away with the iommu=pt kernel parameter, or set log_buf_len=1M to capture the entire dmesg.

Is AMDGPU configured as module or built-in? Please pastebin /proc/config.gz (requires CONFIG_IKCONFIG_PROC enabled in your kernel). It looks like your kernel does not even attempt to initialize it. Also check "lspci -k" whether amdgpu is the driver in use for your graphics card.

I did compile the kernel, installed the modules and installed the kernel, how it is described in the wiki. The last thing, before freezing is "end Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0)"

UPDATE: I will now install grub again to repair the system. I will give you the information, you requested tomorrow morning. Thank you for your help anyway.

Ok, i installed Funtoo again from scratch, since i was confused with the different kernels and i think the wrong kernel (base-debian-kernel?) was used by grub.
How can i make sure, i use the kernel, i configured with make menuconfig? I configure the .config, afterwards i use "make -j7", "make modules_install" and "make install", so the new kernel should be installed right?`Maybe my boot partition is not mounted correctly, when i try to install and thats all the hassle? Because when i "ls /boot", i don't see anything is shown, the directory is empty!
Please help me to understand, why thats is happening, because i thought, my fstab makes sure, that /dev/sdb1 (my boot partition) is mounted under /boot ?!

When your /boot is on a separate partition, you need to ensure that it is mounted before you copy anything there. If fstab contains "noauto" then this mount will not happen automatically.

To prevent accidental writes to /boot, you can change "noauto" to "ro" in fstab, and then run "mount -o remount,rw /boot" each time before you make changes there. Alternatively, run "chattr +i /boot" while not mounted.

After your kernel was installed, you need to ensure that grub knows about it, either through the configuration tool or manually creating a boot entry for it.

So the easiest solution is to manually mount /boot after i configured and installed the kernel and after that copy the bzImage in my /usr/src/linux/arch/x86_64 directory to , where the debian-kernel is in boot directory, so the bootloader loads this new kernel instead of the old one?

"make install && make modules_install" is fine, but copying the kernel manually is of course possible too.

The bootloader will load one of the kernels that has been made known to him in the configuration. Simply existing in /boot is not enough for the kernel to be found, you need to use the configuration tool or manually adjust the config.

After the kernel has booted, you can check "uname -a" build date and time whether you are running the correct kernel.

Funtoo, while similar to Gentoo, is not something that can be officially supported here, so this section is a better fit. It does not mean the issue will be ignored, but the chances of it being solved will be lower due to the differences between the distributions._________________Kind regards,
Chiitoo.

You might remember me from Gentoo projects such as Forums, LXQt, Qt, and Wine.

Last edited by Chiitoo on Thu Jan 14, 2016 8:37 pm; edited 2 times in total

Ok, i just copied the new kernel into my mounted /boot directory and replaced the old kernel. I checked, it is the right one with uname -a.
lspci -l gives me the name of my graphics card Tonga PRO [Radeon R9 285/380], but there is no driver in use.